Peter J. Edmonson

Injection locking techniques for a 1-GHz digital receiver using acoustic-wave devices

The use of surface-transverse-wave (STW) resonator-based oscillators as amplifiers and as carrier recovery elements is discussed. It is demonstrated that these oscillators can amplify phase-shift-keyed signals with very little added noise, while providing a constant output power. Their performance in carrier recovery amplifications is analyzed. Experimental results showing the amplification with more than 80 dB of dynamic range of a 2 Mb/s BPSK signal and the carrier recovery of an 8 Mb/s signal with a 1-GHz STW oscillator are shown.<<ETX>>

Development of a Shear Horizontal SAW RFID Biosensor

RFID tags have been used for passive retrieval of information via retransmission of interrogative radio frequency signals. This paper presents the development of a shear horizontal surface acoustic wave (SH-SAW) RFID biosensor. A 220 MHz SAW device was fabricated on LiNbO3 substrate; composed of an interdigitated transducer (IDT), a dummy electrode, reflectors and a bio-sensitive layer. As the RF interrogation system sends a short RF pulse to the SAW device, the apparent pulse frequency of the return signal shifts due to binding of the biological target which decreases the velocity of the traveling pulse. The biosensor was functionalized by immobilizing anti-FITC on the dummy electrode, and tested against FITC and biocytin (negative control). The frequency shifted by 250 kHz with FITC, and 20 kHz with biocytin. Real-time monitoring of mass loading with deionized water and acetone on the device showed a 3 MHz shift. In addition, the effects of acetone evaporating on the sensor were observed as the device returned to the base frequency.

Mode selection in a multimode SAW oscillator using FM chirp mixing signal injection

Mode-selection control of a multimode surface-acoustic-wave (SAW) oscillator has been obtained using SAW linear FM chirp signal injection. The prototype 60-100-MHz SAW oscillator design employed a single-phase unidirectional transducer (SPUDT) low-loss comb filter in the feedback loop, with minimum insertion loss of approximately=3.7 dB. Mode selection was achieved using an injection signal derived from the mixed output of two 27.5-52.5-MHz up- and down-chirp SAW filters. Mode switching times of <or approximately=2 mu s were obtained. The device could be useful as a local oscillator on frequency-agile radars, where hopping is required over a moderate number of frequencies.<<ETX>>

The Phase Noise Characteristics of a Driven SAW Oscillator in the Threshold Vicinity for Injection Locking

Studies have been conducted on the phase noise of a driven 674 MHz SAW oscillator in the threshold vicinity for injection locking. An automated frequency stability analyzer was used to characterize phase noise and Allan variance, while a low-noise f requency synthesizer was used for injection. 1 Hz 5 fF 5 10 kHz was used for close-in phase noise measurements, while Allan variance U~(N,T,T) was computed over times 0.0001 i T 5 100s. In the l ocked state, it was found experimentally that the SAW oscillator adopted the close-in phase noise characteristics of the low-level (-30 dB down) injection source. This result is explained with reference to the theory of beat spectra in a driven unlocked oscillator. A Fourier frequency fF range

Multifrequency Pulsed Injection-Locked Oscillator Using a Novel Low-Loss SAW Comb Filter

Coupling-of-modes (COM) theory is used in the analysis and design of a SAW single-phase unidirectional transducer (SPUDT) in a low-loss SAW comb filter. Comb separations are given by 1/T, where T = time delay between IDTs within each SPUDT. Devices on lithium niobate yielded insertion losses at comb peaks ranging from 3.7 dB to 9.6 dB over the total comb response with group delays 3 < 1 ps, in excellent agreement with theory. h multifrequency delay line oscillator was obtained using such a comb filter in the feedback loop. With pulsed injection-locking, frequency hopping times of 1-2 ps were realized; as illustrated for a 60-100 MHz SAW oscillator with 0 dBm power level and 10 MHz between individually selectable oscillator frequencies.

SAW-based carrier recovery without phase ambiguity for 915 MHz BPSK wireless digital communications

A surface acoustic wave (SAW)-based nonlinear carrier recovery system for wireless digital communications employing a 915 MHz injection-locked SAW oscillator for demodulation of 2 Mb/s and 8 Mb/s binary phase shift keying (BPSK) input signals is described. The circuit does not permit the injection-locked SAW oscillator to follow the abrupt phase changes in the input BPSK signals, but assumes an output signal with a unique frequency signature that is dependent on the input phase transition. Measurements of the SAW oscillator phase noise are presented, together with receiver input and output spectra and waveforms. An indoor 915 MHz radio transmitter is used with this SAW-based carrier recovery circuit for measurements of bit-error-rate (BER) under fading and non-fading conditions. BERs of less than 4*10/sup -8/ are obtained for 2 Mb/s and 8 Mb/s BPSK signals at 915 MHz, without differential encoding, using a digital transmission analyzer with 2/sup 15/-1 pseudo-random code length.<<ETX>>

Molecular Recognition in the Digital Radio Domain

In this paper we discuss the theoretical and experimental constructs which together point the way towards the transduction of biomolecular recognition events into a palpable set of electrical signals. This combines the applied physics of surface perturbations on acoustic wave device surfaces and the biochemistry of the interactions between an immobilized biomolecule (e.g., an antibody) and a target molecule which is flowing past the sensor surface (e.g., an antigen). We will first provide the theoretical basis for our contention that we can extract information about both molecular recognition and conformational change from the electrical signal and will then confirm this assertion with experimental results relating to induced conformational changes in DNA on a quartz crystal microbalance (QCM) surface. Next we will discuss our digital radio technique whereby the real time measurements using antibody coated surface acoustic wave (SAW) devices in the vapor phase allow us to differentiate between close chemical analogs of nitro-based molecules (e.g., tri-nitro toluene vs musk oil) by virtue of the cross-reactivity of the antibody-antigen interaction. In immunochemistry this is referred to as antibody promiscuity. Finally, we present two- and three-dimensional plots illustrating our technique which derives much from in-phase and quadrature phase (IQ) mapping. The end result is a powerful technique which allows one to differentiate between target molecules and chemically similar interferrents.

Modeling a longitudinally coupled dual-mode leaky-SAW resonator filter with enhanced upper-sideband suppression

Recently, it has been experimentally reported that enhanced upper-sideband suppression of a longitudinally coupled (first/third) dual-mode leaky SAW (LSAW) resonator filter may be obtained by incorporation of a selectively valued capacitor between input and output terminals. In this paper, coupling-of-modes (COM) and bandstop-filter modeling is applied to realize this enhanced suppression. Tradeoffs are examined between upper and lower sideband suppression levels caused by the ensuing capacitive coupling between input and output terminals. Good agreement is obtained between this theory and reported experimental results for an 800-MHz band cellular filter.

Measurements of the Complex Impulse Response of Two-Port SAW Resonators

Measurements are reported on the impulse response of two-port SAW resonators, concerning the non-classical decay of their impulse response envelopes. Network analyzer frequency response data on 90 MHz and 674 MHz SAWRs were used with 401 point inverse discrete Fourier transform (IDFT) software to calculate these patterns. As well, impulse responses were directly obtained using a 1 GHz sampling scope. on the impulse response envelope is explained in terms of (a) power loss per transit through an effective cavity length Lce, (b) the qroup delay 1: With this technique, time-gated IDFT responses can also be applied to S- frequency response data, to obtain a measure of #e frequency response of the SAW grating r eflectors. The observed periodic ripple

Detection of Bacterial Signaling Molecules in Liquid or Gaseous Environments

The detection of bacterial signaling molecules in liquid or gaseous environments has been occurring in nature for billions of years. More recently, man-made materials and systems has also allowed for the detection of small molecules in liquid or gaseous environments. This chapter will outline some examples of these man-made detection systems by detailing several acoustic-wave sensor systems applicable to quorum sensing. More importantly though, a comparison will be made between existing bacterial quorum sensing signaling systems, such as the Vibrio harveyi two-component system and that of man-made detection systems, such as acoustic-wave sensor systems and digital communication receivers similar to those used in simple cell phone technology. It will be demonstrated that the system block diagrams for either bacterial quorum sensing systems or man-made detection systems are all very similar, and that the established modeling techniques for digital communications and acoustic-wave sensors can also be transformed to quorum sensing systems.